In heavy duty applications such as those experienced in automotive applications, especially on or near the engine, vibration and internal loads can be very significant to such an extent that there is high risk of destruction or damage of individual components of an actuator. DC electric motors used in these actuators are typically built with a deep drawn or cup shaped metal housing having an open end closed by a plastic end cap containing brush holders, motor terminals and a bearing which holds and guides the rotor.
Under heavy loading (for the size of the actuator) and under high vibration, the connection between the end cap and the housing is placed under great stress which can lead to the end cap becoming separated from the housing in an extreme situation or simply becoming loose which affects the operation of the motor, increasing audible noise and generally reducing the performance of the motor and thus of the actuator.
Prior art attempts to reduce the effects of vibration on the motor tend to concentrate on stopping vibration from the motor being transmitted to the body or casing of the actuator. For example, U.S. Pat. No. 5,696,360 describes a motor mount used in a vehicle, having an elastic sound-absorbing material used to prevent transmission of vibrations from the motor to the body of the vehicle. This vibration absorbing motor mount must allow the motor to move with respect to the housing to be able to absorb the vibrations. This means that the alignment and spacing between the motor shaft and the gear train is not constant. This is undesirable in a gear train where distances between wheel, worm and any other shaft axes must be kept constant.
Hence there is a desire for a motor mount which supports the motor against vibration, whether the source of the vibration is external or internal of the motor.